Kate Scheer: Dental handpieces – overcoming the aerosol challenge
COVID-19 has forced industries worldwide to adapt quickly to a new state of normality. Dentistry is no exception, with many changes in infection control protocols and associated dental armamentaria expected to arise post-pandemic.
Dentistry is classed as a high-risk profession for the transmission of COVID-19, particularly as aerosols are produced during many day-to-day dental procedures.
Comprised of water, saliva, blood, debris, and microbials such us bacteria, viruses, fungi and protozoa, inhalable aerosols can pose a threat to health.
As dental processes come under greater scrutiny, dental professionals must seek to minimise risks by reducing the amount of aerosol created in general practice. This begins with dental handpieces, especially the high-speed options which create more airborne contamination via aerosol than any other instruments in dentistry, besides ultrasonic equipment .
There is a need for solutions that minimise the risk of spreading infectious agents. For instance, some pre-procedural mouthrinses such as povidone-iodine (PVP-I) are clinically proven to not only reduce the bacterial load and viral contamination of aerosol, but also the inevitability of negative impact caused by aerosols during dental treatment [2,3], although it is important to be aware that solutions such as PVP-I should only be used as a pre-procedural mouthrinse, and not as a cooling or irrigation liquid for equipment.
New technology could also help reduce aerosol in practice. High-speed dental handpieces (e.g. turbines) with anti-retraction systems can be particularly useful in this regard, as they are designed to minimise and offset any negative impacts from the run-out time – which is the moment when the handpiece rotor continues to rotate before stopping – achieved by circulating air within the turbine head to minimise the amount of aerosol being sucked back into the turbine as the rotor comes to a stop.
Some dental turbines and couplings are further enhanced with an anti-retraction valve located within the turbine itself which prevents the backflow of potentially contaminated water particles via the turbine or coupling into the hose, treatment centre and central water supply system, thus providing an additional level of protection.
A recent study has shown that anti-retraction technology can significantly reduce the backflow of oral bacteria and HBV into the tubes of the handpiece and dental unit, which makes handpieces with anti-retraction functions or other anti-reflux designs strongly recommended as an extra preventive measure for cross-infection .
Not all dental handpieces are created equal. Some turbine handpieces produce more exhaust air during use, increasing the amount of aerosol in the environment. This risk can be minimised with the use of straight and contra-angle handpieces; especially if the speed of the handpiece can be adjusted to reduce the amount of aerosol dispersed.
Straight and contra-angle handpieces also tend to operate at lower speeds than dental turbines at a maximum of 200,000 revolutions, which minimises the suction effect of any aerosol.
Aerosol dispersal can be further minimised through robust cleaning and sterilization of dental handpieces. In this case, automatic handpiece maintenance equipment can be of significant benefit. The most reliable systems restrict aerosol to the inside of the handpiece, while filtrating any exhaust material prior to expulsion.
Additionally, these systems confine residual waste solely to the unit to help ensure easier cleaning. The use of automatic handpiece maintenance units also prevents the dental team from breathing in aerosol produced by spray cans of lubricant and other solutions.
It is important to invest in top-quality dental equipment to minimise the risk of disease transmission. At W&H, for example, we design the most effective solutions, including the innovative Synea range of dental handpieces. These are designed with a patented hygiene head, featuring a proven anti-retraction system for minimal aerosol production.
W&H also offers the Assistina TWIN automatic maintenance unit, which is optimised to further reduce the risk of aerosol dispersion via the reprocessing and oiling of handpieces. To find out more, visit www.wh.com/en_uk.
The dental team has always prided itself on maintaining the highest standards of infection prevention and control within the practice, and under the new COVID-19 protocols they want to implement measures that ensure their practices are safe environments for the delivery of first-class treatment, while protecting themselves and their patients, not just from COVID-19, but any potentially harmful disease.
1] Harrel, S. K. and Molinari, J. (2004) Aerosols and splatter in dentistry: a brief review of the literature and infection control implications. Journal of the American Dental Association. 135(4): 429-437. DOI: 10.14219/jada.archive.2004.0207.
2] Eggers, M. (2019) Infectious Disease Management and Control with Povidone Iodine. Infectious Diseases and Therapy. 8(4): 581-593. DOI: 10.1007/s40121-019-00260-x.
3] Eggers, M., Koburger-Janssen, T., Eickmann, M. and Zorn, J. (2018) In Vitro Bactericidal and Virucidal Efficacy of Povidone-Iodine Gargle/Mouthwash Against Respiratory and Oral Tract Pathogens. Infectious Diseases and Therapy. 7(2): 249-259. DOI: 10.1007/s40121-018-0200-7.
4] Peng, X., Xu, X., Li, Y., Cheng, L., Zhou, X. and Ren, B. (2020) Transmission routes of 2019-nCoV and controls in dental practice. International Journal of Oral Science. 12(1): 9. DOI: 10.1038/s41368-020-0075-9.